Characterization of Hydrogen Bonded Liquid Crystals Formed by Suberic Acid and Alkyl Benzoic Acids

Abstract

An inter hydrogen bonded homologous series with seven liquid crystalline complexes has been isolated and characterized. Double complementary hydrogen bonds are formed between a nonmesogen suberic acid (SA) and mesogenic p-n-alkyl benzoic acid (nBA); the series is referred as SA + nBA. Hydrogen bond is evinced by FTIR studies, while the mesogenic phases are identified by polarizing optical microscopic studies that are further substantiated by differential scanning calorimetry. Phase diagram is composed of nematic, smectic C, smectic F, and smectic G phases. The variation of tilt angle of various homologues with temperature in smectic C is fitted to a power law and the exponent value (β) is found to be in agreement with mean field predicted value (0.5). Orders of the various phase transitions are established by Cox method. Dielectric studies enable to identify phases and evaluate relaxation processes in smectic C and the corresponding activation energy is derived from the data.

Keywords:

• Cox ratio
• dielectric spectrum
• hydrogen bonded liquid crystals
• mean field theory
• order of phase transition

Acknowledgments

The divine and graceful blessings of almighty Bannari Amman, the infrastructural support rendered by Bannari Amman Institute of Technology, and the financial support rendered by the Board of Research in Nuclear Sciences (BRNS) of Department of Atomic Energy (DAE), India (Sanction No. 2012/34/35/BRNS), are gratefully acknowledged by the authors.